1. Field of the Invention
The present invention relates to a method of reclaiming a contaminated liquid desiccant, such as glycol, and more particularly, to such a method which recycles a portion of uncondensed vapor to a reboiler through submerged sparge connections.
2. Description of Prior Art
Liquid desiccants, such as diethylene and triethylene glycol, are commonly used for the dehydration of natural gas streams. The dehydration occurs by the mixing of the liquid desiccant with the gas stream and the removal of water therefrom because of the greater affinity of water for glycol than for the natural gas. The moisture-laden glycol is then collected and is heated above the boiling point of the water in order to drive off the water from the glycol. The dehydrated or lean glycol is then recycled into contact with the natural gas stream.
The regeneration or reconcentration of the desiccant by reheating is usually sufficient to remove the water from the desiccant; however, numerous regeneration systems have been designed to more fully reconcentrate the desiccant.
In normal operation of a natural gas dehydration unit with triethylene glycol (TEG) or other high boiling liquid desiccants, thermal decomposition products accumulate in the circulating solution in the form of both solid particles and other higher boiling liquid products. In addition to the accumulation of thermal decomposition products there may be a significant accumulation of dissolved mineral salts originating from entrained water which is often present in the gas feeding the glycol contactor. To prevent premature discard of these solutions various reclaimers have been employed to recover active glycol from the generally non-volatile impurities by means of vacuum distillation. As an example, vacuum conditions have been required to limit the kettle temperatures to an approximate maximum of 400.degree. F. with TEG for the purpose of minimizing decomposition during distillation.